Heat-recuperating process and apparatus for blast-furnaces



l. P..DOVEL.

HEAT RECUPERATING PROCESS AND APPRATUS FOR BLAST FURNACES.

y APPLICATION FILED DEC. 21. |918. 1,316,086. .Patented sept. 16, 1919.

l A if JAMES I? Dove.

THE COLUMBIA PLANouR/wn cn., wASHlNnToN. n. c,

JAMES P. DOVEL, OF BIRMINGHAM, ALABAMA.

HEAT-RECUPERATING PROCESS AND APPARATUS FOR BLAST-FURNACES.

Specicationof Letters Patent.

Patented Sept. 16, 1919.

Application led December 27, 1918.` Serial No. 268,536.

T 0 all lwhom 'it may concern.'

Be it .known that I, Janus P. DovEL, a citizen of the United States ofAmerica, residing at Birmingham, in the county of Jefferson and State ofAlabama, have invented certain new and useful Improvements in HeatRecuperating Processes and Apparatus for Blast-Furnaces, of which thefollowing is a specification.

My invention relates to a heat recuperating process and apparatus forblast furnaces, my object being to devise means whereby the equivalentof a closed circuit may be established for the heat units that haveheretofore escaped from the furnace stoves through the stack toy the endthat by an extremely simple and practicable means the temperature of hotblast may be maintained vhigher without fuel expense than normal or maybe maintained at normal temperature by the use of a less number ofstoves.

A further object of my invention relates to its use in connection with astack induced draft wherein an automatic agency is provided to( permitthe escape from the closed heat circuit of just suflicient heat units tomaintain a uniform stack draft, this being accomplished preferably bymeans `of an automaticvalve responsive to stack temperatures andadjustable to control the voluniey of cold air which is shunted throughthe recuperating agency. By thus maintaining my stack induced draftsubstantially uniform in the stoves, the volume of air and gas canbe soproportioned as to produce perfect combustion and highest eiliciencyfrom the gas consumed, this not being` possible with the irregular,variable draft which is obtained from stacks under the present practice.The air and gases are not admitted to the stoves under the sameconditions, the gas being under pressure,

and the air not being under pressure, and the saine volumes of air andgas are different, and when it is considered that the variable stackinduced draft will affect the entering volume of gas and air to anindefinite degree it will be apparent that the stove valves cannot beadjusted to maintain approximately perfect combustion conditions in thestoves. My invention will greatly assist in this respect by eliminatingthe variable draft and to that extent will simplify the control of thestove valves and improve their operation and stove efficiency.

in section and recuperating coils in side elevation.

Fig. 2 is a plan view of the recuperating coils; and

Fig. 3 is a detail view of the automatic valve and its thermostaticregulator.

Similar reference numerals refer to similar parts throughout thedrawings.

In the embodiment of my invention illustrated, 1 is the hot main leadingfrom the stoves 2 to the blast furnace, not shown, and 3 is the stackflue having a manifold connection controlled by the valves 4 with theseveral stoves at one end and at the other end being connected to thestack 5 or equivalent draft agency. This stack flue is provided with anenlarged recuperating chamber 6 at some intermediate point between thestoves and stack and in this chamber is disposed an air heatingarrangement of any suitable character such as the coils 7 connectedtothe header pipes 8 at each end which inl turn have connection by pipes9 with the cold air main 10 to the stoves. Valves 11 and 12 are providedin the pipes 9 and between the points of connection of said pipes withthe cold air main I interpose a valve fitting 13 having therein astypical of anyvsuitable valve a vertically adjustable gate valve 14:,the stem 15 of which is connected lto a bell crank 16 pivotally mountedon a standard 17a on the pipe 10 and having its vertically disposedcrank arm connected to the free rend of a brass bar 17 forming athermostat, the other end of which is caused to pass slidably through astufling box' 18 at one side' of the stackand to traverse the stackdiametrically and be anchored by plates 19 in the opposite wall of thestack. The bell crank is given adjustable connection to the stem of thevalveby providing the bell crank with a yoke end 20 which works betweenthe nuts 21 screwed on the valve stem'.

In operation, having determined the desired stack temperature necessarto maintain the proper draft, say 400 ahrenheit, the adjustableconnections for the automatic CII QBEST AVALABLE COPY valve areregulated so as to leave this valve fully open when the stacktemperature stands at 400o Fahrenheiufthe valves -11 Pandit 12 beingkeptopen, under which conditions the entering" cold.` air willV be'`shunted pastl the heating coils on its way to the stoves and J`vvillftherefore not be `preheated beforereaching the stoves. As-the, stacktemperature rises above the predetermined maXimumof say `400O-FahrenheitaneXpansion ofthe thermostatic bar results, which in. turnfproduces agradual closing of the` automatic valve in the `cold air main, thereby'shuntinga por-tion of the cold air through the' heating lcoils, thuspreheating the air' and reducing the staclctemperature. As the stacktemperature y'tends yto vary the automatic valve functions tofcontrolthe volu-n` metric flow of. air through thev recuperating f f coils, soproportioning the latter as to eX- y tract all. surplus' heat unitsIfrom the `furnace gases above the predetermineduninr, mum fondraftpurposes,- these heat units are passed backl without -appreciable lossinto 4the stoves, thuscreating a closed circuitfor the heat units fromwhich only a predetermined amountis ermrtted to escape If anarti- Aicialforce draft is employed, the minimum` stack temperaturey may be -reduced-tothe point. wherethe `heat `units are practically j in a closedcircuit.,

There are many important advantages-.-y which flow from--this extremelysimple and c. practical idea forthewrecuperation of heat, f such1forinstance, as: the highly desirable condition ofva uniform draft,thev reduction f? in thefnumber .fof stovesfby reason of thegreater-lengthof timefwhichf the stoves can be useddue-,to the preheatedcondition of the air supplied; the factthe furnace temperatures can-,berun to `abnormal points heretofore'considered impractical by reason fofthe excessiveheat .'losses, known as stack losses; and-fthereduction-'in the amount of fuelrequired for-,the-.blast furnace burden.by reason of the=higher temperatures of the air blast. f"

Iny my pending" application September-- 21st, 1915, `Serial No. 51,882,I have heretoforeproposed to pass the hot gases iowing from .blastfurnace stoves through boilers topartially recover-the waste heat, butit is not possible by such agency to obtain thel contemplated closedcircuit for the waste heat lunits,l nor to exercise reliable controlover the draft, orto lmodify'the functioning ofitheistoves or-the blastfurnace practice as it hasiheretofore prevailed, -all of which are madepossible bythe utilization of the waste heat for -preheating'the-coldair supply to i the stove-in a shunted circuit, and I desire to claimsuch method and the means for practising it broadly and withoutrestrictionsto .the specific! agencies shown.

Having described my invention, what I claim=asnew and-desire to secureby Letters Patent, is

1. The'hereindescribed heat recuperating process for blast furnaces,which consists in transferring heat from the waste gases leaving theblast furnace stovesto-the cold'air blast for1 the furnace, therebysetting up a closed circuit for the heat units, and withdrawingAsuiiicient heat units from said closed circuit to maintain. asubstantially uniform temperature in the gases at their point ofdischarge.`

2. In combination, blast furnace stoves, a main for the wastegasesconducted therefrom, a heat vrecuperating yagencyr exposed to wastegases, and automatic means responsiveto thev temperature of the gasesleaving said .agency to ,pass a predetermined volume of the ccoldairysupplied fto the stoves through'zsaid agency.v

3. In combination, blast furnace stoves, a main l for the waste gasesconducted therefrom, i a heat Yrecuperating agency exposed tol wastegases, :a cold air main `for the stoves, a shunt,circuit-from'fsaid mainwhich4 includes said agency, valve means to control the volume of airshunted through said agency, andthermostatic means responsive to .stackf temperature to `automatically adjustsaid valve means.

4. In'combination, blast furnace stoves, a stack fiue leading therefrom,`a cold air main for` the stoves, a heat recuperating agency in saidflue, .pipe means to shunt cold air from said main through said agency,a valve inrthe cold air main between the points of diversion and returnof'saidshunt air circuit, and a thermostat in the sta-ck forautomatically vkadjusting said valve.

5. In combination, blast `furnace stoves, a stackl flue leadingtherefrom, a cold air main forthe stoves,a heatfrecuperating agency insaidflue, pipe meansy to shunt cold air from said main through saidagency, a valve inthe,` coldair mainfbetween the-points of diversion andreturnof said shunt air circuit,landra thermostat in the stack forautomatically adjusting said valve comprising a metal bar whichtraverses: the stack being anchored thereto at its inner end andconnected to the valveat its outer end, substantially -as described.

Intestimony -whereof I afix my signature.

JAMES P. DOV'EL.

Witness NoMm WELSH. i l

Uopieliof thiLpatentmay-be obtained for ve centseach,lha/'addressing'.the #Commissioner of Patents, Washington, D, GHF.

